Weed mat under raised beds?

[GBax]

I am putting in a few more raised beds made out of railway sleepers. They will be 30cm/12inches high.

I was considering putting some mypex weed mat under the beds as well as under the paths as i am having a battle with ground elder and some kind of bamboo grass.

My question was....apart from the obvious candidate of parsnips will having only 30cm deep soil cause me any problems?

Many thanks for your thoughts

Regards
Guy

[Cadalot]

The guy who had my allotment before me did this with cheap and cheerful weed membrane at a forks depth, made it a bu99er to dig and bits of it come up when I'm digging the plot, then there is the carpet, hardcore and other detritus he buried.

[GBax]

The beds will be no dig so i'm not worried about that factor ......my fear is that it might affect deeper rooted veg

[Martin H]

I would worry about deeper-rooted veg. I would also worry about interfering with earthworm activity and about bits of it working their way to the surface as soil is disturbed when you lift your crops.

So I would put in the hard yards, dig and weed the bottom of the bed thoroughly before filling. I'd put a good thick layer of cardboard at the bottom to help keep the weeds out for the first season.

[Jay-ell]

I'm currently in the process of digging out the weed control fabric that the previous occupants had in the beds on The New Territories.

The weed roots have managed to intertwine through the fabric and use it to extend their water/nutrient gathering capabilities as it wicks the water from all over the bed straight to their roots.

I'm not sure who it was who thought it was a bright idea to plant rhubarb over this stuff nut I had one unhappy rhubarb plant last year with a root system scrunched up in the few inches of soil - its alot happier since I dug it up, hit it with a spade and gave it some depth for it's roots.

[Root66]

I thought about putting a membrane down under the beds at the beginning of the year. Decided against it as it wont stop surface weeds, and I'm sure the deep rooted weeds I sometimes get such as couch grass will penetrate through it anyway, I think bamboo grass would also come through.
I also thought about using paving slabs as I don't grow deep rooting veg in them, however also thought they would move or leave cracks for the weeds to exploit.
I did double dig the area before I built my raised beds, so this has definitely helped. Good luck!

[vixylix]

30cm doesnt seem like a lot of soil depth - I think you've received some sound advice above, however if you do decide to go down the membrane route you need to go a lot deeper, especially for no dig

[Lumpy]

I have just got rid of ours as the beds are only 16in deep and I want (at some point in the future) to put the longer rooted veg in some of them.
I also want the worms in the soil and the matting stops these precious little helpers.

[NickG]

I have done this very thing on our new plot. The plot had been neglected for a few years so once it was strimmer I laid thick quality membrane all over to suppress the weeds. I haven't removed or cut it under the new raised beds as I have planned to do this bed by bed next year. Obviously this goes against what others suggest but I'm buggered if I'm going to do it this year

Worked well this way last year on our old plot. The only exception was the bed I was growing parsnips in. Carrots were in tubs and spuds in sacks

[burnie]

My three raised beds are all built from railway sleepers(well un creosoted same size timbers) I put a double layer of membrane under to keep the same weeds and a few shrub roots out. Only been there for a year, but had no problems so far, mine are double height(2 sleepers on top of each other), but are not yet full. I even grew Parsnips that just turned when they hit the membrane and carried on growing. I am tending to go for shorter carrots this year and the Parsnips will also still go in the beds.